Two new lignans from the rhizomes of Sinomenium acutum

Sinomenium acutum (Menispermaceae) is a deciduous shrub that grows in Asia, particularly Japan, China, and Korea. The stems and roots of the plant are widely used to treat various rheumatic diseases, allergy, dropsy, and dermatophytosis in the traditional Chinese prescriptions. Previous phytochemical investigations on S. acutum have reported to isolate various alkaloids, e.g. protoberberine-type, aporphine-type, isoaporphine-type, and morphine-type alkaloids and some of these components showed antiinflammatory, anticancer, immunosuppressive, and arthritis ameliorative activities. In our continuing investigation for bioactive constituents from Korean medicinal plant sources, we investigated the MeOH extract of the rhizomes of S. acutum, since the extract showed significant cytotoxic activity in our screening procedures. Column chromatographic isolation of the extract furnished two new lyoniresinol-type lignans (1-2), together with four known lignans (3-6). The identification and structural elucidation of these new compounds were based on 1D and 2D NMR, and HR-FABMS data. The absolute configurations of the new compounds (1-2) were clarified by CD study. We are studying the cytotoxic activities of isolates by determining their inhibitory effects on the human tumor cell lines (A549, SK-OV-3, SK-MEL-2, and HCT-15) using a SRB assay.